The present invention relates to a liquid crystal display device and, more particularly, to an improvement in a driver circuit thereof.
An active matrix type of liquid crystal display device has transparent substrates disposed to oppose each other with a liquid crystal interposed therebetween, gate signal lines disposed on a liquid-crystal-side surface of one of the transparent substrates in such a manner as to be extended in the x direction and to be juxtaposed in the y direction, and drain signal lines disposed on the liquid-crystal-side surface in such a manner as to be extended in the y direction and juxtaposed in the x direction. Areas surrounded by the adjacent gate signal lines and the adjacent drain signal lines are formed as pixel areas. Each of the pixel areas is provided with a switching element driven by the supply of a scanning signal from the corresponding one of scanning signal lines and a pixel electrode to which a video signal is supplied from one of the video signal lines via the switching element.
A scanning signal driver circuit for supplying scanning signals to the respective gate signal lines and a video signal driver circuit for supplying video signals to the respective drain signal lines are mounted, and each of these driver circuits is made of a semiconductor device (IC) mounted on one of the transparent substrates.
This semiconductor device is formed by so-called tape carrier bonding, and is formed by preparing a film substrate having a hole formed in its central portion except its periphery, forming interconnection layers on at least one surface of the film substrate so that the interconnection layers are extended from the hole to the periphery, positioning a semiconductor chip in the hole, and bonding each bump of the semiconductor chip to one end (terminal) of the corresponding one of the interconnection layers which are formed to protrude into the hole.
Incidentally, this semiconductor device, for example, a video signal driver circuit (similarly to a scanning signal driver circuit) includes drain signal lines the plural adjacent ones of which are grouped, and plural semiconductor devices which supply video signals to the respective grouped drain signal lines.
With the recent increase in the number of pixels per liquid crystal display device, the number of gate signal lines and drain signal lines per device has also increased, and the number of bumps of the above-described semiconductor device has had to be increased.
It has been pointed out that, in this case, the semiconductor chip has a shape in which the length of the semiconductor chip in the juxtaposition direction of signal lines connected thereto is larger than the widthwise length of the semiconductor chip, so that during the formation of semiconductor chips on a surface of one semiconductor wafer by so-called step-and-repeat exposure, there occurs the disadvantage that the exposure cannot be effected with accuracy.
The present invention has been made on the basis of such circumstances, and provides a liquid crystal display device provided with a driver circuit capable of fully coping with an increase in the number of pixels per liquid crystal display device.
The outline of a representative aspect of the invention disclosed herein will be described below in brief.
A liquid crystal display device according to the present invention basically has signal lines for driving individual pixels and a driver circuit connected to the signal lines, on a liquid-crystal-side surface of either one of substrates disposed to oppose each other with a liquid crystal interposed therebetween. The driver circuit includes a film substrate, interconnection layers formed on a surface of the film substrate, and a semiconductor chip mounted on the film substrate. Some of the interconnection layers are connected to the bumps of the semiconductor chip, and then run under the semiconductor chip and extend to the periphery of the film substrate.
In the liquid crystal display device constructed in this manner, the interconnection layers which lead out the bumps of the semiconductor chip are formed in the area of the film substrate on which the semiconductor chip is mounted, whereby even if multiple bumps are formed on a semiconductor chip having a limited size, the bumps can be fully led out via the interconnection layers.